Swathing continuous inkjet printers are well known in the art, and are described, for example, in U.S. Pat. No. 6,511,163, and European Patent Application No. EP1197334, which are both herein incorporated by reference. These types of printers generally employ a pair of deflection electrodes that deflect ink drops fired from a nozzle to produce a divergent set of drop paths called a swath. The width of this swath, measured between the two outermost drop paths, typically needs to be calibrated to maintain a predetermined drop spacing and to ensure that drops deposited in adjacent swaths do not overlap. Swathing printers usually perform this type of calibration with a probe or camera that is located away from the print substrate, and this configuration prevents printing and calibration from taking place at the same time.